The quest for high-redshift radio galaxies - I. A pilot spectroscopic study Alessandro Capetti, Barbara Balmaverde, Miguel Coloma Puga, Bruno Vizzone, Ana Jimenez-Gallardo, Abigail García-Pérez and Giacomo Venturi A&A, 697 (2025) A238 Published online: 22 May 2025 DOI: 10.1051/0004-6361/202553967